Lens Barrel and Imaging Device

ABSTRACT

A lens barrel  11  is mounted to a collapsible imaging device  1  having a zooming function and includes a cam frame  19 , a first lens frame  39 , a second lens frame  45 , and a third lens frame  55 . First, second, and third lens frame cam grooves  25, 27, 29 , respectively including in the longitudinal direction thereof insertion parts  25   a   , 27   a   , 29   a , collapse parts  25   b   , 27   b   , 29   b , and variable power parts  25   c   , 27   c   , 29   c  are formed in the inner peripheral face of the cam frame  19 . The third lens frame cam groove 29 are deeper than the first and second lens frame cam grooves  25, 27  and are intersected at the collapse parts  29   c  thereof with the respective insertion parts  25   a   , 27   a.

TECHNICAL FIELD

The present invention relates to a lens barrel and an imaging deviceincluding the lens barrel, and particularly relates to a lens barrelextended from an image plane side to an object side in shooting and animaging device including the lanes barrel.

BACKGROUND ART

Particularly in recent years, percentages of home with digital stillcameras (hereinafter referred to as DSCs) or digital video camerasincrease, and DSCs and compact DSCs having an image stabilizingfunctions are developed for contemplating an increase in convenience.

For example, Patent Document 1 discloses a zoom lens barrel (lensbarrel) which is compacted by devising the arrangement of cams (camgrooves) in a cam frame. Specifically, the document discloses thatbottomed cams are provided on both of the inner peripheral face and theouter peripheral face of the cam frame, the cam on the inner peripheralface and the cam on the outer peripheral face are arranged so as tocross each other at least one position, and one come groove is formed soas to be divided at at least one position, thereby achieving anefficient arrangement of the cams in a small space to minimize thedimension of the cam frame in the direction of the optical axis. As aresult, a zoom lens barrel is reduced in size.

-   Patent Document 1: Japanese Patent Application Laid Open Publication    No. 7-191249A

SUMMARY OF THE INVENTION Problems that the Invention is to Solve

In the zoom lens barrel disclosed in Patent Document 1, however, thecams are provided on the inner peripheral face and the outer peripheralface of the cam frame, which complicates much the structure of the camsin the cam frame.

In addition, four kinds of cams are formed on the inner peripheral faceof the cam frame, resulting in intersection with one another. This mayinhibit the cam pins mounted to the lens frame from sliding in the camsmoothly or derail the cam pins from the cams.

The present invention has been made in view of the foregoing and has itsobject of providing a lens barrel in which a cam groove structure in thecam frame is simplified and which can inhibit the lens frame and thelike from derailing in use, and of providing an image device includingthe lens barrel.

Means for Solving the Problems

A lens barrel according to the present invention is a lens barrel havinga zooming function which includes: a cylindrical cam frame which iscapable of moving along a direction of an optical axis and whichincludes an inner peripheral face in which a plurality of cam groovesare formed; and a plurality of lens frames arranged inside the cam framewith a longitudinal direction thereof aligned with that of the camframe. Wherein the plurality of lens frame are formed so as to receivelenses so that the lenses are arranged and mounted in the cam frame withoptical axes thereof aligned with each other, and the plurality of lensframes include cam pins capable of being engaged with the plurality ofcam grooves. Each of the plurality of cam grooves includes in alongitudinal direction thereof: an insertion part formed so that acorresponding cam pin is movable in the longitudinal direction thereofwhile being engaged therewith when the plurality of lens frames areinserted in the cam frame; a collapse part formed so that acorresponding cam pin is movable in the longitudinal direction thereofwhile being engaged therewith when the plurality of lens frames move inthe direction of the optical axis; and a variable power part formed sothat a corresponding cam pin is movable in the longitudinal directionthereof while being engaged therewith when the plurality of lens framesare zoomed. Further, at least one cam groove out of the plurality of camgrooves are formed deeper than the other cam groove, and in the collapsepart of the relatively deep cam groove, which is formed deeper than theother cam groove, an intersection intersected with the insertion part ofthe other cam groove are formed.

An imaging device of the present invention includes the lens barrel ofthe present invention.

Effects of the Invention

The present invention simplifies a cam groove structure in a cam frameand prevents a lens frame and the like from derailing in use.

BRIEF DESCRIPTION OF THE DRAWINGS

[FIG. 1] FIG. 1(a) is a perspective view of an imaging device in acollapsed state, and FIG. 1(b) is a perspective view of the imagingdevice in a shooting state.

[FIG. 2] FIG. 2 is an exploded perspective view showing a structure of alens barrel.

[FIG. 3] FIG. 3 is a development of an inner peripheral face of a camframe.

[FIG. 4] FIG. 4 is a perspective view of the inner peripheral face ofthe cam frame.

[FIG. 5] FIG. 5(a) is a sectional view taken along the line VA-VA inFIG. 4, and FIG. 5(b) is a sectional view taken along the line VB-VB inFIG. 4.

[FIG. 6] FIG. 6 is an exploded perspective view showing a structure of athird lens frame when viewed from an object side.

[FIG. 7] FIG. 7 is an exploded perspective view showing the structure ofthe third lens frame when viewed from an image plane side.

[FIG. 8] FIG. 8 is a vertical sectional view of the lens barrel in acollapsed state.

[FIG. 9] FIG. 9 is a plan view of the third lens frame when viewed fromthe object side.

[FIG. 10] FIG. 10 is a sectional view taken along the line X-X in FIG.9.

[FIG. 11] FIG. 11 is a vertical sectional view of the lens barrel in anextended state.

[FIG. 12] FIG. 12 is a vertical sectional view of the lens barrel undervariable power control.

[FIG. 13] FIG. 13 is a vertical sectional view of the third lens framebefore detection of a zooming origin.

[FIG. 14] FIG. 14 is a vertical sectional view of the third lens framebefore detection of a focus origin.

[FIG. 15] FIG. 15 is a vertical sectional view of the third lens frameafter detection of the focus origin.

EXPLANATION OF REFERENCE NUMERALS

1 imaging device

11 lens barrel

19 cam frame

25, 27, 29 first, second, and third lens frame cam grooves (a pluralityof cam grooves)

25 a, 27 a, 29 a insertion parts

25 b, 27 b, 29 b collapse parts

25 c, 27 c, 29 c variable power parts

26 intersection

20 39, 45, 55 first, second, and third lens frames

43, 53, 56 first, second, and third cam pins

Best Mode for Carrying out the Invention

An embodiment of the present invention will be described below withreference to the drawings.

Embodiment 1

Embodiment 1 exemplifies, as an image device 1, a DSC incorporating animaging element E, such as a CCD (charge coupled device) for describinga structure of the imaging device 1, a structure of a lens barrel 11incorporated in the imaging device 1, and an operation of the lensbarrel 11 with reference to FIG. 1 to FIG. 15.

-Structure of Imaging Device 1-

First, a structure of the imaging device 1 will be described withreference to FIG. 1. FIG. 1(a) is a perspective view of the imagingdevice 1 in a collapsed state, and FIG. 1(b) is a perspective view ofthe imaging device 1 in a shooting state.

In the imaging device 1 in a non-use state, as shown in FIG. 1(a), thelens barrel 11 is accommodated inside a device casing 3. For use, apower button 5 is pushed to allow the lens barrel 11 to extend from thedevice casing 3, as shown in FIG. 1(b). Namely, in use, the lens barrel11 moves in a direction of the optical axis toward an object to be shotfrom an image plane side. This enables shooting at an arbitrary zoomratio.

-Structure of Lens Barrel 11-

A structure of the lens barrel 11 will be described next with referenceto FIG. 2 to FIG. 10. FIG. 2 is an exploded perspective view showing thestructure of the lens barrel 11. FIG. 3 is a development of an innerperipheral face of a cam frame 19. FIG. 4 is a perspective view of theinner peripheral face of the cam frame 19. FIG. 5(a) is a sectional viewtaken along the line VA-VA in FIG. 4, and FIG. 5(b) is a sectional viewtaken along the line VB-VB in FIG. 4. FIG. 6 and FIG. 7 are explodedperspective views showing a structure of a third lens frame 55, whereinFIG. 6 is an exploded perspective view when viewed from an object sideand FIG. 7 is an exploded perspective view when viewed from the imageplane side. FIG. 8 is a vertical sectional view of the lens barrel 11 ina collapsed state. FIG. 9 is a plan view of the third lens frame 55 whenviewed from the object side and specifically is a plan view of the thirdlens frame 55 from which a shutter unit 57 is taken away. FIG. 10 is asectional view taken along the line X-X in FIG. 9. Hereinafter, “theimage plane side” and “the object side” imply the image plane side andthe object side of the members when assembled, respectively.

The lens barrel 11 includes, as shown in FIG. 2, a fixed frame 13, thecam frame 19, a sliding frame 31, a first lens frame 39, a second lensframe 45, the third lens frame 55, and a master flange 123, all of whichare made of resin, such as polycarbonate.

The master flange 123 is, as shown in FIG. 2, substantially aplate-shaped member having the same diameter as the fixed frame 13, isarranged so as to cover the end faces on the image plane side of thefixed frame 13 and the like, and is fixed to a predetermined part (notshown) of the device casing 3. Further, the master flange 123 includes afixed lens fitting portion 125 and a positioning protrusion 127 (shownin FIG. 13) on the object side and includes an imaging element fixingpart (not shown) on the image plane side.

The fixed frame 13 is a cylindrical member as shown in FIG. 2. Three camframe grooves 15 and three sliding frame grooves 17 are formed in theinner peripheral face of fixed frame 13. The cam frame grooves 15, 15,15 are formed at regular intervals left in the peripheral direction andextend from the middle on the image plan side to the end on the objectside of the fixed frame 13 nonlinearly. The sliding frame grooves 17,17, 17 are arranged at regular intervals left in the peripheraldirection and extend from the end on the image plane side to the middleon the object side thereof longitudinally without being intersected withthe cam frame grooves 15. The fixed frame 13 includes a zooming motor(not shown).

The cam frame 19 is, as shown in FIG. 2, a cylindrical member having adiameter smaller than the fixed frame 13 and a length substantially thesame as the fixed frame 13. In the outer peripheral face on the imageplane side of the cam frame 19, three fixed frame cam pins 21, 21, 21are provided at regular intervals left in the peripheral direction. A.gear portion 23 is formed at the outer peripheral end part on the imageplane side thereof. In the inner peripheral face thereof, first, second,and third lens frame cam grooves (a plurality of cam grooves) 25, 27, 29are formed.

The number of the first lens frame cam groove 25 is three, as shown inFIG. 3 and FIG. 4, and they are arranged at regular intervals left inthe peripheral direction of the cam frame 19. The same is applied to thesecond and third lens frame cam grooves 27, 29. Each of the first lensframe cam grooves 25 extends the farthest toward the object side, andeach second lens frame cam groove 27 and each third lens frame camgroove (relatively deep groove) 29 are formed nearer to the image planeside in this order. The first, second, and third lens frame cam grooves25, 27, 29 are formed so that first pins 43 (described later) of thefirst lens frame 39, second cam pins 53 (described later) of the secondlens frame 45, and third cam pins 56 (described later) of the third lensframe 55 are engaged with the grooves 25, 27, 29 and are movable in thelongitudinal direction thereof, respectively.

As shown in FIG. 3, the first, second, and third lens frame cam grooves25, 27, 29 each include, from the image plane side in this order,insertion parts 25 a, 27 a, 29 a, collapse parts 25 b, 27 b, 29 b, andvariable power parts 25 c, 27 c, 29 c in the longitudinal direction ofthe grooves. Each of the insertion parts 25 a, 27 a, 29 c is formedstraight in parallel with the longitudinal direction of the cam frame 19from the end on the image plane side thereof, and the collapse parts 25b, 27 b, 29 b and the variable power parts 25 c, 27 c, 29 c are curved.The respective collapse parts 29 b of the third lens frame cam grooves29 are intersected with the respective insertion parts 25 a, 27 a of thefirst and second lens frame cam grooves 25, 27, as shown in FIG. 3 andFIG. 4.

Referring to the sections of the grooves, as sown in FIG. 3 and FIG. 4,each third lens frame cam grove 29 is formed deeper, specifically,approximately 0.5 mm deeper, preferably, approximately 1.0 mm deeperthan the first and second lens frame cam grooves 25, 27. Atintersections 26, as shown in FIG. 5(a), the third lens frame camgrooves 29 are formed so that the respective third cam pins 56 move withtheir tip end portions engaged therewith while the parts other than thetip end portions of the third cam pins 56 move without being engagedtherewith. Specifically, the third lens frame cam grooves 29 are formedso that the third cam pins 56 are capable of being engaged with parts ofthe third lens frame cam grooves 29 from the groove bottom faces toparts intersected with the first and second lens frame cam grooves 25,27 in the depth direction of the grooves while being incapable of beingengaged with parts thereof from the parts intersected therewith to theopenings. Herein, the tip end portion of each third cam pin 56preferably ranges 0.5 mm from the tip end in the height direction of thethird cam pin 56 and more preferably ranges 1.0 mm from the tip end inthe height direction of the third cam pin 56. In the vicinity of theintersections, specifically, in regions approximately 0.5 mm apart fromthe intersections 26, more preferably, in regions approximately 3 mmapart from the intersections 26, the third lens cam grooves 29 includestepped portions 29 d, as shown in FIG. 5(b). On the open side from thestepped portions 29 d, the groove width of the third lens frame camgrooves 29 is wider, preferably, approximately 0.03 mm wider, morepreferably, approximately 0.2 mm wider than the pin width of parts ofthe third cam pins 56 which correspond to the cam grooves 29. On theother hand, on the groove bottom side from the stepped portions 29 d,the groove width of the third lens frame cam grooves 29 is substantiallythe same as the pin width of the parts of the third cam pins 56 whichcorrespond to the cam grooves 29.

The sliding frame 31 is a cylindrical member having a diameter smallerthan the cam frame 19 and a length substantially the same as the fixedframe 13, as shown in FIG. 2. Three pairs of sliding grooves 32, 33, 34are formed in the side face thereof so as to pass from the outerperipheral face to the inner peripheral face in a directionsubstantially parallel with the longitudinal direction of the cylinder.Each pair of sliding grooves includes a first lens frame sliding groove32, a second lens frame sliding groove 33, and a third lens framesliding groove 34, wherein the first lens frame sliding grooves 32 arethe longest of all, and the third lens frame sliding grooves 34 are theshortest of all. At the end on the image plane side of the sliding frame31, a stopper rib 35 extends outward from the sliding frame 31, andthree fixed frame protrusions 37, 37, 37 are arranged at the outerperipheral parts of the stopper rib 35 at regular intervals left in theperipheral direction.

The first lens frame 39 is, as shown in FIG. 2, a cylindrical memberhaving a diameter smaller than the sliding frame 31 and a lengthslightly shorter than the fixed frame 13. A zoom lens fitting portion 41is formed at the end on the object side thereof, and three first campins 43 (only one of them is shown in FIG. 2) are arranged at the end onthe image plane side in the outer peripheral face thereof at regularintervals left in the peripheral direction. The first cam pins 43 aretapered as they go toward their tip ends.

The second lens frame 45 includes, as shown in FIG. 2, a cylindricalmember 47 having a diameter smaller than the first lens frame 39 and alength shorter than the first lens frame 39 and three legs 49, 49, 49.The cylindrical member 47 includes on the object side thereof one lensfitting portion 51 capable of receiving three lenses. The legs 49 arearranged at and connected with the end part on the image plane side ofthe cylindrical member 47 at regular intervals left in the peripheraldirection, and second cam pins 53 are arranged at tip ends of the outerperipheral faces of the legs 49. The second cam pins 53 are tapered asthey go toward their tip ends.

The third lens frame 55 includes, as shown in FIG. 6 and FIG. 7, ashutter unit 57, a vibration compensation actuator 71, a lens frame mainbody 95, a focus lens frame 105, and a restricting member 113 in thisorder from the object side, and is further provided with a focus motor115.

The focus motor 115 includes a motor section 117, a lead screw 119, anda nut piece 121. The lead screw 119 is arranged coaxially with and isconnected to the motor section 117. The nut piece 121 is arrangedsymmetrically with the axis thereof as a center of symmetry and isconnected to the lead screw 119.

The lens frame main body 95 includes a through hole portion 97 forallowing light to pass therethrough. A yaw guide shaft mounting portion(not shown) is formed on the object side of the lens frame main body 95.While, two guide poles 101, 101 are press fitted to the image plane sidethereof so as to be substantially opposite to each other with theoptical axis interposed, and a nut piece insertion hole 103 is formedunder one of the guide poles 101. Three third cam pins 56, 56, 56 areformed so as to extend away from the optical axis. The third cam pins 56are tapered as they go toward their tip ends and have a height largerthan the first and second cam pins.

The focus lens frame 105 includes a focus lens fitting portion 107. Onthe object side of the focus lens frame 105, a focus spring receiver111, a nut piece engaging portion 109, and a protrusion 105 a (see FIG.13 through to FIG. 15) are formed. The nut piece engaging portion 109 isformed under the focus spring receiver 111, and the protrusion 105 aprotrudes toward the object side.

The restricting member 113 is mounted on the image plane side of the nutpiece engaging portion 109 of the focus lens frame 105 so as to restrictthe movable range of the nut piece 121.

The vibration compensation actuator 71 is composed of a yaw frame 85, apitch frame 73, two multilayer printed circuit boards 77, 79, a powersupply flexible substrate 83, two magnets 91, 91, and two yokes 93, 93.

The yaw frame 85 includes a through hole portion 87 for allowing lightto pass therethrough, two yaw guide shafts 88, 90, and a pitch guideshaft 89 so as to move correction lenses L5, L6, L7 in the yaw directionfor compensating image blurring in the yaw direction. The yaw guideshafts 88, 90 are opposed to each other substantially in parallel withthe yaw direction so that that the yaw frame 85 is mounted to the lensframe main body 95 movably in the yaw direction. The pitch guide shaft89 is arranged in parallel with the pitch direction so that the pitchframe 73 is movable in the pitch direction.

The pitch frame 73 includes a correction lens fitting portion 75 and apitch guide shaft 86 so as to move the correction lenses L5, L6, L7 inthe pitch direction for compensating image blurring in the pitchdirection. The pitch guide shaft 86 is arranged substantially inparallel with the pitch direction on the opposite side of the opticalaxis to the pitch guide shaft 89 of the yaw frame 85 so that the pitchframe 73 is mounted to the yow frame 85 movably in the pitch direction.

Each multilayer printed circuit board 77, 79 is formed of stackedsubstrates of multiple layers (generally four layers) in which coils 76,78 are printed. One 77 of the multilayer printed circuit boards isconnected to a vertically extending end face of the pitch frame 73 whilethe other multiplayer printed circuit board 79 is connected to atransversely extending end face of the pitch frame 73. Hole sensors 81,81 for detecting the positions of the correction lenses L5, L6, L7 areincorporated in the multilayer printed circuit boards 77, 79,respectively. The power supply flexible substrate 83 extends from themultilayer printed circuit boards 77, 79, bends from the pitch frame 73toward the image plane side, bends once toward the object side, and thenbends toward the image plane side again. The two printed circuit boards77, 79 may be formed integrally.

Each magnet 91 is a plate magnet. Each yoke 93 has a substantiallyhook-like shape in section.

The shutter unit 57 includes a disk-shaped support frame having athrough hole portion 59 for allowing light to pass therethrough, ashatter actuator 61, a diaphragm actuator 63, a power supply flexiblesubstrate 65, and an origin sensor 67. The shutter actuator 61 and thediaphragm actuator 63 are boarded on the surface on the object side ofthe support frame. The power supply flexible substrate 65 is mounted onthe surface on the object side of the support frame. One end of thepower supply flexible substrate 65 bends toward the image plane side, isoverlapped in the middle thereof with the power supply flexiblesubstrate 83 of the pitch frame 73, bends once toward the object side,and then bends toward the image plane side again. The other end of thepower supply flexible substrate 65 extends outward from the supportframe to serve as a focus motor connecting portion 69. With the abovearrangement, the power supply flexible substrate 65 is connectedelectrically to the shutter actuator 61, the diaphragm actuator 63, theorigin sensor 67, and the motor section 117 of the focus motor 115. Theorigin sensor 67 is mounted on the image plane side of the support frameso as to detect a focus origin and a zoom origin.

-Arrangement in Lens Barrel-

The arrangement in the lens barrel 11 will be described next.

In the lens barrel 11, the positioning protrusion 127 of the masterflange 123 presses the focus lens frame 105. As shown in FIG. 8, thefixed frame 13 is arranged at the outermost side of the lens barrel 11.The cam frame 19, the sliding frame 31, the first lens frame 39, and thesecond lens frame 45 are arranged in this order toward the inside. Thethird lens frame 55 is arranged the innermost side thereof. In detail,the fixed frame cam pins 21 are engaged with the cam frame grooves 15 ofthe fixed frame 13 so that the cam frame 19 is arranged inside the fixedframe 13. The fixed frame protrusions 37 are engaged with the slidingframe grooves 17 of the fixed frame 13 so that the sliding frame 31 isarranged inside the cam frame 19.

In the first lens frame 39, the first cam pins 43 pass through the firstlens frame sliding grooves 32 of the sliding frame 31 and are engagedwith the insertion parts 25 a of the first lens frame cam grooves 25 ofthe cam frame 19. The first cam pins 43 pass the intersections 26 andmove in the longitudinal direction of the insertion parts 25 a to theboundary between the insertion parts 25 a and the collapse parts 25 bwith the engaged state thereof maintained. Whereby, the first lens frame39 is arranged inside the sliding frame 31. Similarly, in the secondlens frame 45, the second cam pins 53 pass through the second lens framesliding grooves 33 of the sliding frame 31 and are engaged with theinsertion parts 27 a of the second lens frame cam grooves 27 of the camframe 19. The second cam pins 53 pass the intersections 26 and move inthe longitudinal direction of the insertion parts 27 a to the boundarybetween the insertion parts 27 a and the collapse parts 27 b with theengaged state thereof maintained. Whereby, the second lens frame 45 isarranged inside the first lens frame 39.

In the third lens frame 55, the third cam pins 56 pass through the thirdlens frame sliding grooves 34 of the sliding frame 31 and are engagedwith the insertion parts 29 a of the third lens frame cam grooves 29 ofthe cam frame 19. The third cam pins 56 move, without passing theintersections 26, in the longitudinal direction of the insertion parts29 a to the boundary between the insertion parts 29 a and the collapseparts 29 b with the engaged state thereof maintained. Whereby, the thirdlens frame 55 is arranged inside the second lens frame 45.

At the intersections 26, as shown in FIG. 5(a), the tip ends of thethird cam pins 56 are engaged with the groove bottom side of the thirdlens frame cam grooves 29 while parts other than the tip ends thereofare not engaged with the open side of the third lens frame cam grooves29. In the vicinity of the intersections 26, specifically, in regionsapproximately 0.5 mm apart from the intersections 26, more preferably,in regions approximately 3 mm apart from the intersections 26, the thirdlens frame cam grooves 29 and the third cam pins 56 are separated fromeach other on the open side from the stepped portions 29 d of the thirdlens frame cam groove 29 while the third lens frame cam grooves 29 andthe third cam pins 56 are in contact with each other on the groovebottom side from the stepped portions 29 d of the third lens frame camgrooves 29.

-Arrangement in Third Lens Frame 55-

An arrangement in the third lens frame 55 will be described next.

As shown in FIG. 6 and FIG. 7, in the third lens frame 55, the shutterunit 57, the pitch frame 73, the yaw frame 85, the lens frame main body95, and the focus lens frame 105 are arranged in this order so that thethrough hole portion 59 of the shutter unit 57, the correction lensfitting portion 75 of the pitch frame 73, the through hole portion 87 ofthe yaw frame 85, the through hole portion 97 of the lens frame mainbody 95, and the focus lens fitting portion 107 of the focus lens frame105 are overlapped with one another.

On the image plane side of the lens frame main body 95, as shown in FIG.7, one end of the focus spring (an elastic member) 110 is inserted inone of the guide poles 101 while the other end of the focus spring 110is urged against the focus spring receiver 111 of the focus lens frame105. This causes the focus lens frame 105 to urge the lens frame mainbody 95 by means of the focus spring 110. In the focus motor 115, greaseis applied to the lead screw 119, and the nut piece 121 passes throughthe nut piece insertion part 103 of the lens frame main body 95 and isengaged with the nut piece engaging portion 109 of the focus lens frame105. Further, the restricting member 113 is arranged on the image planeside of the nut piece 121.

On the other hand, on the object side of the lens frame main body 95,the yaw frame 85 is mounted to the lens frame main body 95 movably inthe yaw direction in such a fashion that the yaw guide shafts 88, 90 ofthe yaw frame 85 are mounted to the yaw guide shaft mounting portions ofthe lens frame main body 95. The pitch frame 73 is mounted to the yawframe 85 movably in the pitch direction in such a fashion that the pitchguide shaft 89 of the yaw frame 85 is mounted to the pitch guide shaftmounting portions. The yokes 93, 93 include, as shown in FIG. 6,hook-like spaces in which the magnets 91, 91 are housed to form magneticfields, and are inserted in and fixed to the lens frame main body 95from the outer periphery so that the coils 76, 78 of the multilayerprinted circuit boards 77, 79 mounted to the pitch frame 73 are arrangedin the magnetic fields. The power supply flexible substrate 65 of theshutter unit 57 is overlapped with the power supply flexible substrate83 of the pitch frame 73 so that the shutter unit 57 is fixed at theouter peripheral part of the lens frame main body 95.

When viewing the third lens frame 55 from the image plane side or theobject side, as shown in FIG. 9, the three third cam pins 56, 56, 56 areformed at regular intervals left in the peripheral direction. The originsensor 67 is arranged at a drawing point 129 of the power supplyflexible substrate. The motor section 117 of the focus motor 115 isarranged on a site having a larger angle out of angles formed byconnecting the one multiplayer printed circuit board 77 and the othermultilayer printed circuit board 79 with one point on the optical axis.In other words, the motor section 117 of the focus motor 115 is arrangedin a region other than a region interposed between the one multiplayerprinted circuit board 77 and the other multilayer printed circuit board79. Though not shown in FIG. 9, the motor section 117 of the focus motor115, the shutter actuator 61, and the diaphragm actuator 63 are arrangedalong the inner peripheral face of the cylindrical member 47 of thesecond lens frame 45 so as not to intercept the light.

As shown in FIG. 6 and FIG. 7, the shutter unit 57 is arranged on theobject side of the vibration compensation actuator 71 in the directionof the optical axis. Further, as shown in FIG. 10, the motor section 117of the focus motor 115 is arranged on the object side of the correctionlenses L5, L6, L7, namely, on the object side of the vibrationcompensation actuator 71, similarly to the shutter unit 57.

-Operation of Lens Barrel 11-

An operation for extending the lens barrel 11 and an operation for focusadjustment will be described next with reference to FIG. 8, FIG. 11, andFIG. 12. FIG. 11 is a vertical sectional view of the lens barrel in anextended state, and FIG. 12 is a vertical sectional view of the lensbarrel under variable power control.

The operation for extending the lens barrel 11 will be described first.

The lens barrel 11 is in the state as described above until the power issupplied to the imaging device 1. Namely, all of the cam frame 19, thesliding frame 31, the first lens frame 39, the second lens frame 45, andthe third lens frame 55 are located inside the fixed frame 13. Usually,a zoom lens L1 having a positive refractive index is fitted in the lensfitting portion 41 of the first lens frame 39, three lenses L2, L3, L4having a negative refractive index in total are fitted in the lensfitting portion 51 of the second lens frame 45, the three correctionlenses L5, L6, L7 having a positive refractive index in total are fittedin the correction lens fitting portion 75 of the pitch frame 73 of thethird lens frame 55, and the focus lens L8 is fitted in the focus lensfitting portion 107 of the focus lens frame 105 of the third lens frame55. The fixed lens L9 is fitted in the lens fitting portion 125 of themaster flange 123, and the imaging element E is fixed to the imagingelement fixing portion. The respective numbers of lenses fitted to thefirst, second, and third lens frames 39, 45, 55 and thepositive/negative refractive indices of the lenses are not limitedthereto.

When the power is supplied to the imaging device 1, the lens barrel 11is extended as shown in FIG. 11.

Specifically, when the power is supplied to the imaging device 1, thezooming motor of the fixed frame 13 rotates to rotate the gear portion23 of the cam frame 19. This rotates the cam frame 19 in the peripheraldirection. Specifically, the cum frame 19 moves in the longitudinaldirection with the cam frame pins 21 engaged with the cam frame grooves15 of the fixed frame 13 to be extended toward the object side. At thesame time, the sliding frame 31 is extended together with the cam frame19 toward the object side without being rotated with the fixed frameprotrusions 37 engaged with the sliding frame groves 17 of the fixedframe 13. As well, in association with extension of the cam frame 19,the first, second, and third lens frames 39, 45, 55 are extended towardthe object side without being rotated in such a state that the first,second, and third cam pins 43, 53, 56 pass through the first, second,and third lens frame sliding grooves 32, 33, 34 of the sliding frame 31,respectively, and are engaged with the first, second, and third lensframe cam grooves 25, 27, 29 of the cam frame 19, respectively. In thisstate, the distance between the second lens frame 45 and the first lensframe 39 is small while the distance between the second lens frame 45and the third lens frame 55 is large, which means that the lens barrel11 is in the WIDE extremity position presenting the widest angleoptically.

In the case where the lens barrel 11 is extended and then themagnification is set high, the cam frame 19 is further extended towardthe object side. Also, the first, second, and third lens frames 39, 45,55 are moved relatively in the longitudinal direction along the camgrooves 25, 27, 29. As a result, as shown in FIG. 12, the distancebetween the second lens frame 45 and the first lens frame 39 becomeslarge while the third lens frame 55 approaches the second lens frame 45,so that the lens barrel 11 is in the TELE extremity position presentingthe largest zoom magnification optically.

The operation for focus adjustment will be described next.

For adjusting the focus, the motor section 117 of the focus motor 115 isdriven first to rotate the lead screw 119. The nut piece 121 is engagedwith a guide portion 103, which is provided at the third lens frame 55in the direction of the optical axis, so as to be inhibited fromrotating and, therefore, is movable in the direction of optical axis bythe rotation of the lead screw 119. The focus lens frame 105 is urgedall the time by the focus spring 115 toward the image plane side so asto be engaged with the nut piece 121 at the nut piece engaging portion109. With this arrangement, the focus lens frame 105 is moved in thedirection of the optical axis together with the nut piece 121 to changethe distance between the pitch frame 73 and the focus lens frame 105.Namely, the distance between the correction lenses L5, L6, L7 and thefocus lens L8 is changed so that the focus is adjusted.

-Operation of Origin Sensor 67-

An operation of the origin sensor 67 will be described next withreference to FIG. 13 to FIG. 15. FIG. 3 to FIG. 15 are sections takenalong the line X-X in FIG. 9. FIG. 13 is a view showing a structure ofthe third lens frame 55 before the zoom origin is detected and shows thecollapsed state. FIG. 14 is a view showing a structure of the third lensframe 55 before the focus origin is detected and shows the state wherethe focus lens is located the nearest to the object side. FIG. 15 is aview showing a structure of the third lens frame 55 after the focusorigin is detected and shows the state where focus lens is located thenearest to the image plane side.

In detecting the zoom origin, as shown in FIG. 13, the lens barrel 11 isin the collapsed state first. In the collapsed state, the positioningprotrusion 127 of the master flange 123 presses the focus lens frame105. Further, the nut piece 121 is just arranged slightly away from therestricting member 113 on the object side and is not engaged with thefocus lens frame 105. In other words, the positioning protrusion 127 ofthe master flange 123 sets the position of the focus lens frame 105 withrespect to the third lens frame 55.

When the zooming motor is driven, the third lens frame 55 is extended.At extension, the focus lens frame 105 remains pressed by thepositioning protrusion 127 of the master flange 123 so as not to beextended toward the object side. On the other hand, driving the zoomingmotor results in extension of the lens frame main body 95 toward theobject side. Accordingly, the lens frame body member 95 is moved awayfrom the focus lens frame 105 in the direction of the optical axis. Atthis movement, the protrusion 105 a of the focus lens frame 105 passesthe center of the origin sensor 67, so that that zoom origin isdetected. Thus, driving the zooming motor results in origin detection.When the extension is continued to allow the focus lens frame 105 to beengaged with the nut piece 121, the focus lens frame 105 is extendedtogether with the third lens frame 55 so that the lens barrel 11 is inthe WIDE extremity position capable of shooting. In this state, thethird lens frame 55 is extended sufficiently toward the object side, sothat the focus lens frame 105 is out of contact with the positioningprotrusion 127 of the master flange 123.

Next, in detecting the focus origin, when the motor section 117 of thefocus motor 115 is driven and the lens barrel 11 is extended to be inthe WIDE extremity position in FIG. 11, the lead screw 119 is rotated tomove the nut piece 121 and the focus frame 105 toward the object side,thereby allowing the lens barrel 11 to be in the state shown in FIG. 14.

Subsequently, when the focus motor 115 is rotated in the reversedirection, the nut piece 121 moves the focus lens frame 105 toward theimage plane side. As a result, as shown in FIG. 15, the protrusion 105 aof the focus lens frame 105 passes the center of the origin sensor 67.Accordingly, the origin sensor 67 detects the focus origin. Namely,driving the focus motor results in origin detection.

-Effects by Lens Barrel 11-

As described above, in the cam frame 19 of the lens barrel 11, the thirdlens frame cam grooves 29 are intersected at the collapse parts thereofwith the respective insertion parts of the fist and second lens framecam grooves 25, 27. Further, the third lens frame cam grooves 29 areformed deeper than the first and second lens frame cam grooves 25, 27.Accordingly, at the intersections 26, the third cam pins 56 move in thelongitudinal direction of the deeper grooves while being engaged withthe deeper grooves, to be prevented from derailing from the third lensframe cam grooves 29.

Further, the first and second lens frame cam grooves 25, 27 areintersected at the respective insertion parts 25 a, 27 a with the thirdlens frame cam grooves 29, which means that the intersections 26 areformed in regions other than region where the first and second cam pins43, 53 pass in use. Accordingly, the first and second cam pins 43, 53 donot pass the intersections 26 in operation to be prevented fromderailing.

In sum up, since the third lens frame cam grooves 29 are deeper than thefirst and second lens frame cam grooves 25, 27, the third cam pins 56are prevented from derailing at the intersections 26. On the other hand,the first and second cam pins 43, 53 do not pass the intersections 26 inoperation, resulting in no derailing thereof at the intersections 26.

Moreover, as described above, the first and second cam pins 43, 53 areprevented from derailing from the first and second lens frame camgrooves 25, 27, respectively, in operation, eliminating the need toprovide a derailment preventing member additionally. Hence, the camframe 19 can be manufactured at low cost.

At the intersections 26 and in the vicinity of the intersections 26, thethird lens frame cam grooves 29 are formed so that the third cam pins 56moves with the tip ends thereof engaged with the third lens frame camgrooves 29 and with no other parts thereof engaged with the third lensframe cam grooves 29. Namely, in the middle of and in the front and rearregions of the intersections 26, the third cam pins 56 slide on thethird lens frame grooves 29 with the groove bottom sides thereof fromthe step portions 29 d being always in contact with the third lens framecam grooves 29, so as not to be in discontinuous contact with the wallface on the groove open sides thereof at the boundary part of theintersections 26. Hence, continuous and smooth sliding can be achievedeven at the intersections 26, leading to smooth extension of the lensbarrel 11.

The imaging device 1 includes the lens barrel 11, achievingsubstantially the same effects as the lens barrel 11.

Embodiment 2 of the Invention

A lens barrel and an imaging device of Embodiment 2 are substantiallythe same as those in Embodiment 1, wherein the structure of the camgrooves in the cam frame are different. Specifically, while the thirdlens frame cam grooves are formed deeper than the first and second lensframe cam grooves as well, the third lens frame cam grooves areintersected at the collapse parts thereof with the respective collapseparts of the first and second lens frame cam grooves.

At the intersections, the third lens frame cam grooves are so formed, asshown in FIG. 5(a), that the third cam pins moves with the tip endsthereof engaged with the third lens frame cam grooves and with no otherparts thereof engaged with the third lens frame cam grooves. Further, inthe vicinity of the intersections, as shown in FIG. 5(b), the third lensframe cam grooves include the step portions. The groove width of thethird lens frame cam grooves are wider than the pin width ofcorresponding parts of the third cam pins on the open sides from thestep portions while being substantially the same as the pin width ofcorresponding parts of the third cam pins on the groove bottom sidesfrom the step portions.

As described above, even though the first and second lens frame camgrooves are intersected with parts of the third lens frame cam groovesother than the insertion parts, the third cam pins can move smoothly atthe intersections and in the vicinity of the intersections because onlythe tip ends of the third cam pins are in contact with the third lensframe cam grooves at the intersections and in the vicinity of theintersections.

It is noted that the first and second cam pins may have an ellipticalshape long in the traveling direction at the intersections so as not toderail at the intersections.

Other Embodiments

Any of the following arrangements may be employed in Embodiments 1 and2.

Any of the following arrangements may be employed in the presentembodiments.

The focus motor 115 includes the motor section 117, the lead screw 119coaxial with the motor section 117, and the nut piece 121 of which axisserves as the symmetric center, but the lead screw 119 may not benecessarily coaxial with the motor section 117 and may be reversedthrough a transmission mechanism.

In the case where the lead screw 119 is reversed, the motor section 117or the lead screw 119 of the focus motor 115 may not be necessarilyarranged on the site having the larger angle out of the angles formed byconnecting the one multilayer printed circuit board 77 and the othermultilayer printed circuit board 79 with one point on the optical axisand may be arranged in a region where the multilayer printed circuitboards 77, 79 are not arranged. Specifically, the motor section 117 maybe arranged on the site having the smaller angle out of the aboveangles, namely, may be arranged in a region interposed between the onemultilayer printed circuit board 77 and the other multilayer printedcircuit boards 79.

The origin sensor 67 is arranged at the drawing point 129 of the powersupply flexible substrate, but may be arranged in a region where themultilayer printed circuit boards 77, 79, the motor section 117 of thefocus motor 115, the third cam pins 56, the second cam pins 53 of thesecond lens frame 45, and the like are not arranged.

Furthermore, the first, second, and third cam pins 43, 53, 56 aretapered as they go toward their tip ends, but may be cylindrical. In thecase where the first, second, and third cam pins are formedcylindrically, the respective first, second, and third lens frame camgrooves are preferably formed so as to be engage with the respectivecylindrical cam pins.

Moreover, the imaging device 1 may be a single lens reflex camera ofwhich lens is detachable or a compact camera of which lens is notdetachable.

The lens barrel 11 includes the first, second, and third lens frames 39,45, 55, but the number of lens frames is not limited to three.

The first, second, and third lens frame cam grooves 25, 27, 29 areformed in the cam frame 19, but the first lens frame cam grooves 25, thesecond lens frame cam grooves 27, and the third lens frame cam grooves29 are formed in the first, second, and third cam frames, respectively,so that each cam frame is capable of being driven. In this way, the camframes may be provided correspondingly to the respective cam grooves soas to be driven separately.

In addition, the numbers of lenses fitted to the first, second, andthird lens frames 39, 45, 55 are not limited to the numbers eachdescribed above. As well, positive/negative refractive indices of thelenses fitted to the first, second, and third lens frames 39, 45, 55 arenot limited to the above described combination.

The third lens frame cam grooves are intersected at the collapse partsthereof with the respective collapse parts of the first and second lensframe cam grooves in Embodiment 2, but the third lens frame cam groovesmay be intersected at the variable powers thereof with the respectivecollapse parts of the first and second lens frame cam grooves, or may beintersected at the collapse parts thereof with the respective variablepower parts of the first and second lens frame cam grooves. The thirdlens frame cam grooves may be intersected at any of the insertion parts,the collapse parts, and the variable power parts thereof with the firstand second lens frame cam grooves, or the first and second lens framecam grooves may be intersected at any of the respective insertion parts,the respective collapse parts, and the respective variable power partsthereof with the third lens frame cam grooves.

INDUSTRIAL APPLICABILITY

As described above, the present invention is useful for lens barrels andimaging devices. Particularly, the present invention is useful for lensbarrels having a zooming function and imaging devices including the lensbarrels.

1. A lens barrel having a zooming function, comprising: a cylindricalcam frame which is capable of moving along a direction of an opticalaxis and which includes an inner peripheral face in which a plurality ofcam grooves are formed; and a plurality of lens frames arranged insidethe cam frame with a longitudinal direction thereof aligned with that ofthe cam frame, wherein the plurality of lens frame are formed so as toreceive lenses so that the lenses are arranged and mounted in the camframe with optical axes thereof aligned with each other, and theplurality of lens frames include cam pins capable of being engaged withthe plurality of cam grooves, each of the plurality of cam groovesincludes in a longitudinal direction thereof: an insertion part formedso that a corresponding cam pin is movable in the longitudinal directionthereof while being engaged therewith when the plurality of lens framesare inserted in the cam frame; a collapse part formed so that acorresponding cam pin is movable in the longitudinal direction thereofwhile being engaged therewith when the plurality of lens frames move inthe direction of the optical axis; and a variable power part formed sothat a corresponding cam pin is movable in the longitudinal directionthereof while being engaged therewith when the plurality of lens framesare zoomed, at least one cam groove out of the plurality of cam groovesare formed deeper than the other cam groove, and in the collapse part ofthe relatively deep cam groove, which is formed deeper than the othercam groove, an intersection intersected with the insertion part of theother cam groove are formed.
 2. The lens barrel of claim 1, wherein therelatively deep cam groove is formed so that a corresponding cam pinmoves with the tip end thereof engaged with the relatively deep camgroove and with no other part thereof engaged with the relatively deepcam groove at the intersection and in the vicinity of the intersection.3. The lens barrel of claim 2, wherein the cam pins are formed taperedas they go toward their tip ends, in the vicinity of the intersections,in cross section, the relatively deep cam groove includes a stepportion, and a groove width of the relatively deep cam groove is widerthan a pin width of the cam pins on an open side from the step portionwhile being substantially the same as the pin width of the cam pins on agroove bottom side from the step portion.
 4. A lens barrel having azooming function, comprising: a cylindrical cam frame which is capableof moving along a direction of an optical axis and which includes aninner peripheral face in which a plurality of cam grooves are formed;and a plurality of lens frames arranged inside the cam frame with alongitudinal direction thereof aligned with that of the cam frame,wherein the plurality of lens frame are formed so as to receive lensesso that the lenses are arranged and mounted in the cam frame withoptical axes thereof aligned with each other, and the plurality of lensframes include cam pins capable of being engaged with the plurality ofcam grooves, each of the plurality of cam grooves includes in alongitudinal direction thereof: an insertion part formed so that acorresponding cam pin is movable in the longitudinal direction thereofwhile being engaged therewith when the plurality of lens frames areinserted in the cam frame; a collapse part formed so that acorresponding cam pin is movable in the longitudinal direction thereofwhile being engaged therewith when the plurality of lens frames move inthe direction of the optical axis; and a variable power part formed sothat a corresponding cam pin is movable in the longitudinal directionthereof while being engaged therewith when the plurality of lens framesare zoomed, at least one cam groove out of the plurality of cam groovesare formed deeper than the other cam groove, and the relatively deep camgroove, which is formed deeper than the other cam groove, includes anintersection interested with the other cam groove and is formed so thata corresponding cam pin moves with the tip end thereof engaged with therelatively deep cam groove and with no other parts thereof engaged withthe relatively deep cam groove at the intersection and in the vicinityof the intersection.
 5. The lens barrel of claim 1, wherein first,second, and third cam grooves are formed in the inner peripheral face ofthe cam frame, and one of the first, second, and third cam grooves isthe relatively deep cam groove.
 6. An imaging device comprising the lensbarrel of claim
 1. 7. An imaging device comprising the lens barrel ofclaim 4.